Optical pre-amplification is widely used for example to increase photoreceivers sensitivity in order to improve the distance for data transmission over optical fiber in digital communication systems. In such systems cost is typically an important issue to be considered. In this regard, monolithic integration of a semiconductor optical amplifier (hereinafter also referred to as SOA) and a photodetector in one InP single chip become particularly important as it may contribute to reducing cost of the receiver terminal as well as its size.